David L Rubin 1 CESR Test Accelerator Investigation of the physics of charged particle beams Circumference 768m Beam energy 1855 GeV Electrons and Positrons November 18 2011 ID: 400664
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Slide1
November 18, 2011
David L. Rubin
1
CESR Test Accelerator – Investigation of the
physics of charged particle beams
Circumference = 768m - Beam energy 1.8-5.5
GeV
- Electrons and PositronsSlide2
November 18, 2011
David L. Rubin
2
Linear Collider
Energy/beam = 250-500 GeV
E
CM
= 0.5-1.0
T
eVSlide3
November 18, 2011
3
David L. Rubin
Electron cloudSlide4
Shielded pickup
November 18, 2011
David L. Rubin
4Slide5
Shielded Pickup
November 18, 2011
David L. Rubin
5
With no magnetic field, electrons come from the floor of the chamberSlide6
Cloud Evolution: Witness Bunch Studies
TiN
Chamber
November 18, 2011
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David L. Rubin
Cloud is generated by the first bunch. The witness bunch follows and kicks the
cloud electrons into the pickup. Decay time of the cloud is evident. Slide7
Example:
Positron Witness Bunch Study at 2GeV
November 18, 2011
David L. Rubin
7
Peak SEY Scan
Coherent Tune Shifts (1 kHz ~ 0.0025), vs. Bunch Number
- 21 bunch train, followed by 12 witness bunches
- 0.8×10
10
particles/bunch
- 2
GeV
.
- Data (black) compared to POSINST simulations.
SEY=2.0
SEY=1.8
SEY=2.2
Train
WitnessesSlide8
November 18, 2011
David L. Rubin
8
Low
emittance
tuning procedure typically yields sub 20pm in one or two iterations
σ
=
17μm
ε
v
= 18pm
D-line
xbsm
- positronsSlide9
32 Channel Detector
Output For 20 Bunches, 1 mA Per Bunch
November 18, 2011
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David L. Rubin
C-line – electron beam size
20 bunches,14 ns spacing, 32 channels, pinhole optics
Capability to measure bunches spaced by as few as 4nsSlide10
November 18, 2011
10
David L. Rubin
C-line – electron beam size
Joe
Calvey
– Electron cloud
Jim Shanks – Low
Emittance
Tuning
Mike
Ehrlichman
– Intra-beam scattering
CesrTA
Grad studentsSlide11
November 18, 2011
David L. Rubin
11Slide12
November 18, 2011
David L. Rubin
12Slide13
November 18, 2011
David L. Rubin
13Slide14
November 18, 2011
David L. Rubin
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